I used to be like that. The thing that really changed my mentality was spending a few years consulting. Doing that put my brain in CEO/Owner mode instead of "worker bee" mode. The paradigm shift is one you can never go back from. Now, regardless of whether I'm in regular job or a contract job I only work for myself and only make decisions related to my work for my own benefit. Now I can leave a job/contract with zero emotional baggage, even though I sometimes make friendships that live longer than the job/contract.
Even if I'm an "employee" in my mind I'm the owner of a one-man company that sells IAM/development services. Sometimes I have to dump one customer to service another that's going to pay me more money or let me work fewer hours. Work ethic and my personal reputation matters to me, but I don't care one whit if my employer goes belly up.
As they lower you into the paupers grave I'm sure your boss will deliver a moving eulogy about how you were such a asset to the business and created so much shareholder value.
Well, probably more amazing than someone who doesn't see themselves as providing a valuable service to their employer, and is just turning up to collect their paycheck.
I am similar, having been a contractor for about a third of my working life. And even when I was permanent I rarely lasted longer than 2 years with a company, due to mergers and redundancies and bad management.
I'm currently in a perm role, been here nearly 3 years and quite happy to stay for a bit longer. I've been to a couple of interviews in that time that headhunters put in front of me, but I'm not actively looking. I like my current place, but I'm not married to it.
Your job is a transaction. You're there for the money, not out of charity. If they won't pay you your market worth, they're taking advantage of you and you should leave.
Even if I'm an "employee" in my mind I'm the owner of a one-man company that sells IAM/development services. Sometimes I have to dump one customer to service another that's going to pay me more money or let me work fewer hours. Work ethic and my personal reputation matters to me, but I don't care one whit if my employer goes belly up.